Wednesday, March 23, 2016

How Quickly Can a Vampire Drain Your Blood?

Vampires, those mythical creatures that feast on human blood depicted
in Bram Stoker’s “Dracula,” have now undergone the scrutiny of
academia.Science students at the University of Leicester’s Department of Physics and Astronomy
wanted to know how quickly a vampire could feed on a human. To coincide
with the 85th anniversary of Universal Picture’s classic “Dracula”
starring Bela Lugosi, they used fluid dynamics to examine how long it
would take a vampire to drain enough blood for sustenance and not enough
to kill the host.

Carotid Artery in the Neck

The student team determined that a vampire would puncture the
external carotid artery in a human’s neck. The aorta, or main artery, of
the body, splits into five arteries. For the study, they were concerned
with the velocity of blood flowing into only the common carotid artery.
By examining the average human blood pressure in arteries measured
relative to the air pressure, this gave the students a pressure
difference.Next, they determined an average density of blood at room temperature
and were able to deduce how much blood would come out of a puncture in a
human’s neck. They assumed that a vampire’s fangs leave puncture holes
with a width of 0.5mm each.The human body has an average of 5 litres of blood, a vampire might
take 15%. The team used 15% as a benchmark, as any more blood loss would
cause the heart rate to change, while less can be taken without
affecting the circulatory system of the human.Thus, it was determined that a vampire would drain 0.75 litres of
blood, and by their calculations it would take 6.4 minutes to do so.The students reported their findings in the peer-reviewed student journal run by the university’s physics and astronomy department. Course tutor Dr. Mervyn Roy says,

Every year we ask each student to write around 10 short
papers for the Journal of Physics Special Topics. It lets students show
off their creative side and apply some physics they know to the weird,
the wonderful, or the every day.